The Ecology Book

290

domestic use, and 11 percent for

industry. However, most aquifers

replenish much more slowly than

they can be emptied, so water

yields reduce with use. If the water

table falls, some lakes and rivers dry

up. About half the total length of

China’s rivers has been lost since

1990. In North America, the Great
      Lakes are shrinking, Lake Winnipeg
      is threatened, and the massive

Ogallala aquifer is being depleted.

There are even water supply

problems in Brazil, which is the

most water-rich nation on Earth. As

the situation worsens, it becomes

a growing source of conflict.

Water scarcity

There are two types of water

scarcity. Physical water scarcity

affects regions that naturally do

THE WATER CRISIS

Water stress around the world

None

1–9 months

10–12 months

This map illustrates the

average exposure of water users

to water stress—the ratio of

total withdrawals to total

renewable supply in a given

area. A higher proportion of

withdrawals means that more

water users are competing for

limited supplies.

The desiccation of the Aral Sea

The disappearance of most of the

Aral Sea, once the world’s fourth-

largest lake, in Kazahkstan has

been a huge ecological disaster.

In the early 1960s, the two main

rivers that fed the lake were

diverted to irrigate millions of

cotton plants across central Asia.

In June 2004, the UN warned that

the lake could dry up completely

unless measures were taken to

save it. It was then receiving only

10 percent of the water that it

once did, had divided into several

smaller lakes, and contained only

one-tenth of its 1960 volume of

water. Large areas are now

desert. Most of the lake’s fish

and other aquatic life disappeared

with its water. Once fishermen

here could catch Syr Darya

sturgeon, but its numbers

declined sharply when the lake

shrank and became more saline.

Efforts to replenish the waters

have achieved an increase in

surface area and depth, and fish

populations are now increasing.

A stranded ship on the dried-up

bed of the Aral Sea. The loss of such

a large body of water has had a

devastating effect on agriculture,

climate, and the local fishing industry.

KEY

not have plentiful water, such as

North Africa, the Arabian Peninsula,

large areas of central and south

Asia, northern China, and the

southwest United States. In contrast,

economic water scarcity occurs

when water is available but the

infrastructure does not exist to

utilize it. This is the situation in

much of sub-Saharan Africa and

parts of Central America. People

Los Angeles

New York

Mexico City

Rio de Janeiro

Sao Paulo

London

Istanbul

Cairo

Mumbai

Delhi

Beijing Tokyo

Osaka

Shanghai

Major cities

experiencing

water scarcity

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